1. Field of the Invention
The present invention relates to the field electrically operable wheelchairs. More particularly, the invention hereof concerns a wheelchair including a pair of support wheels coupled with a pair of drive motors, one of a plurality of different types of user-operable input devices, and a controller responsive to input signals from the input devices for controlling the operation of the motors and thereby the movements of the wheelchair. The controller is operable to respond to the different types of input signals provided by the devices for producing outputs to the motors for effecting the desired wheelchair movements.
2. Description of the Prior Art
The prior art discloses electrically operable wheelchairs which typically include a battery, a pair of motors respectively coupled with the main support wheels, a user-operable input device such as a joy stick or a set of switches, and a controller coupled with the input device and the motors for controlling the operation thereof in order to effect desired wheelchair movements. The input device provides input signals representative of desired wheelchair movements to the controller. Different types of input devices are required to accommodate the needs of the user. While a joy stick provides the greatest degree of control, some users do not have the physical ability to operate a joy stick, and as a result must use a set of switches.
The input signals from each type of device are characteristic of that device. For example, a joy stick provides proportional control analog signals and switches provide on-off digital signals. Because of these differing signal characteristics, the associated controller must be designed to respond to the particular type of input signals. This means that if a different type of input device is installed on a wheelchair, the controller must also be changed which adds substantially to the cost because the controller typically costs more than the input device. Additionally, the need to manufacture different types of controllers requires larger inventories and reduces the length of production runs which factors further increased costs.